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911st 911st is offline
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Join Date: Jan 2004
Location: Sacramento
Posts: 7,269
Good move Dave!!!

Mostly good info here.

It is interesting to see him making more HP than TQ with a stock cams. This raises a question as that is not typical of stock cams or even SC cams in many cases.

Looks like full boost is being had at about 3600rpm. A properly set up K27-7200 can get there by about 3000-3200rpm.

As noted it is trade offs in the following area's.

1000-2300rpm Idle to where the turbo is making power. (cams, timing, more compression, twin plugs, displacement).

3000-3800rpm where full boost is obtained. (turbo size and configuration mostly)

4000-5500 meat of the power band and where all cams work well.

5500-red-line, where the big HP lives. (turbo efficiency, cams, sufficient AFR, breathing)

Most turbos and cams are going to do about the same in the 4000-5500rpm range. It is the area's before and after that can be effected significantly with other choices. Even the stock cams and ports can probably do within 10hp in that area. Increasing efficiency will help most in this area, better intercooler, higher boost, bigger motor, more ideal AFR and timing.

Thus, assuming all the basic goods like boost, intercooler, headers -- the basic trade for most is a fuller 2000 - 4000rpm range or big HP(+30 to a lot more) in the 5000-7000rpm range.

In my case I had an extreme build 3.3 CIS turbo. I gave up that big rush or pull past 5500rpm and about 30-50hp -- for boost that came in hard and was full in by 3000rpm but going from a K29 and then an early HF back to a K27-7200.

Do note that after about 350rwhp the K27-7200 is moving out of its efficiency island and it starting to heat the intake are more than a larger turbo. Have not seen many get to 400rwhp and I could not push it past about 375rwhp with ports, headers, cams, and large intercooler.

Last edited by 911st; 04-23-2010 at 08:11 AM..
Old 04-23-2010, 07:44 AM
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